Demolition hammers are used on work sites to break up objects such as rocks, concrete, asphalt, frozen ground, or other hard objects. The hammers may be mounted to machines, such as backhoes and excavators, or may be hand-held. The hammers may be powered by a hydraulic or pneumatic pressure source. In operation, a high-pressure fluid drives a piston to strike a tool bit, which in turn, strikes rock, concrete, asphalt or other hard object to be broken up.
Lubrication systems are used to supply lubricant, such as grease, to bearing surfaces in the hammer to reduce friction between moving parts, such as between the tool bit and bushings that are used to align the tool bit. The lubrication system may be separate from the hammer, for example by being mounted on a carrier machine, or mounted to the hammer, i.e., an on-board system. Whether externally mounted or on-board, a lubricant supply is provided with the system. Conventional lubrication systems for demolition hammers can be complicated and include hydraulic motors that drive camshafts. Furthermore, operating demolition hammers without lubrication can result in significant damage to the hammer.
In the system of U.S. Pat. No. 9,643,310 B2 to Moore, a lubrication system includes a drive fluid valve member and a detune valve member. The drive fluid valve member is movable from a first to a second position in response to drive fluid pressure to reduce the volume of a variable volume lubricant charge chamber. The detune valve member is movable from a first to a second position in response to lubricant pressure within the lubricant charge chamber, and is adapted to permit fluid communication between inlet and bypass fluid passages in its the first position and to disengage the fluid connection in its second position.